Before the present invention, there was no facile method for obtaining cPLA.sub.2 in substantial quantities. Human cPLA.sub.2 and a method of purification is described in U.S. patent application Ser. No. 07/573,513. Antibodies reactive with cPLA.sub.2 and methods for isolating and identifying cPLA.sub.2 are described in U.S. patent application Ser. No. 07/663,335. At best those methods are capable of providing only limited amounts of cPLA.sub.2 because of its scarcity in the cytoplasm of cells which naturally contain it. To illustrate the extremely rare nature of cPLA.sub.2 and to highlight the problem solved by this invention, it need only be mentioned that less than 100 ugs of cPLA.sub.2 exists in all of the cells present in an 80 liter culture of a human monocytic cell line. Thus, the present invention overcomes the difficulties of obtaining relatively large amounts of this rare and important enzyme.
Phospholipase A.sub.2 (PLA.sub.2) is the common name for phosphatide 2-acylhydrolase which catalyzes the hydrolysis of the sn-2 acyl ester bond of phosphoglycerides producing equimolar amounts of lysophospholipids and free fatty acids (Dennis, E. A., The Enzymes Vol. 16, Academic Press, New York,(1983)). Phospholipase A.sub.2 enzymes are found in all living species and form a diverse family of enzymes. Of those studied co date, the vast majority have a molecular weight of approximately 14 kDa, and their amino acid sequences show great homology.
The most abundant and commonly studied PLA.sub.2 enzymes are the secreted forms. These enzymes are produced within the cell, packaged into secretory vesicles and later released into the extracellular environment where they aid in the digestion of biological material. In contrast, cPLA.sub.2 is found in vanishingly small amounts, remains within the cell and serves in an entirely different capacity than the secreted forms. Thorough investigation of intracellular PLA.sub.2 s has been hampered by the extremely low concentration of these enzymes in cells (Vadas and Pruzanski, Lab. Investigation, 55, 4: 391 (1986)).
The ability to modulate receptor mediated cPLA.sub.2 activity via specific inhibitors is a desirable goal and may lead to new therapies for the treatment of asthma, ischemia, arthritis, septic shock, and inflammatory diseases of the skin. The inactivation or specific inhibition of cPLA.sub.2 activity associated with particular disease states will be of great use to the medical community. To accomplish this goal, cPLA.sub.2 presumed to be involved in the pathogenesis of certain diseases must first be identified and isolated. This has been done and was described in an earlier filed U.S. patent application mentioned above. The present invention provides genes which encode cPLA.sub.2, vectors and host cells which are useful for expressing cPLA.sub.2 and methods for expressing cPLA.sub.2.